The invention is in the field of nuclear magnetic resonance (NMR) and more particularly to coils to be wound around a cylindrical sample-containing body oriented at a selected angle with respect to a predetermined direction for generating a magnetic field of which the component in this predetermined direction will vary linearly along the axial direction of the cylindrical body.
It is a standard procedure of analysis by magnetic resonance to rotate a sample at a high speed in a uniform magnetic field to obtain an improved average homogeneous sample volume. It is also characteristic of certain specific experiments to orient the rotational axis of the sample at a selected angle with respect to this uniform magnetic field. The selected angle is usually the so-called magic angle which is equal to the root of the equation 3 cos2 xcfx86xe2x88x921=0, or about 54.7xc2x0.
In some applications, it is desirable to generate a magnetic field of which the component in the direction of the uniform field changes linearly along a specified direction such as the axial direction of rotation of the sample-containing cylinder.
It is therefore an object of this invention to provide a device having a cylindrical body and means for establishing a magnetic field of which the component along a predetermined direction varies linearly along the axial direction of the cylindrical body.
A device embodying this invention, with which the above and other objects can be achieved, may be characterized wherein the cylindrical body with its axis of symmetry making a non-zero angle xcfx86 is surrounded by a pair of coils of the same shape which are in mutually parallel planes, overlapping each other as seen perpendicularly to these planes and wherein the normal line to these planes make an angle xcex1 nearly equal to 2xcfx86xe2x88x9290xc2x0 from the predetermined direction.